firstly check all connections are solid incuding sensor wire
step 2 try a new sensor wire if it works job done if it doesn't step go to step 3
step3 refit old sp motor see if fault returns
my son currently runs a lrp x20 6.5 with reventon pro its only crap when we forget to put the sensor wire back
other wise its fine
I have heard of sensor boards failing but more with SP motors
dave